The present invention relates generally to shirred casing articles of the type wherein a length of shirred casing is carried on a tubular core member. More particularly, the invention relates to such an article including means for restraining the ends of a compacted length of shirred casing to prevent axial growth of the casing with respect to the core member. The invention also relates to a method and apparatus for capturing a fully compacted length of shirred casing.
Shirred tubular casings are well known in the art. Such casings are extensively used in food processing to make a variety of sausage type products and in the packaging of larger food products, such as cooked and smoked hams and the like.
Briefly, during the shirring process, relatively long lengths o. casing are shirred, by any one of several conventional techniques, to produce a relatively short, tubular strand of shirred casing. Still further length reduction is accomplished by subjecting the strand of shirred casing to an axial force so as to compact the pleats formed by shirring. Depending on the size and length of the casing, the force applied to compact a shirred strand may exceed 1000 pounds or more. The end result is that it is not uncommon in the art to have a compact strand of shirred casing which is only about 1% of the length of the unshirred casing. The degree of compaction is expressed in terms of a pack ratio (PR), which is the ratio of the casing length to the length to the compacted strand. For example, depending upon the diameter and wall thickness of the casing, as well as other factors, it is not uncommon to obtain pack ratios of 100 or more. That is, a compacted strand measuring one foot in length may contain 70 to 100, or more, feet of casing. Such a compacted strand is referred to in the art as a "stick".
One drawback of these compacted strands of shirred casings, or sticks, is that the stick is resilient. It will begin to grow or elongate as soon as the compaction force is released. This growth is most rapid immediately after the stick is formed, and gradually diminishes over a period of time. Accordingly, this growth may continue for at least part of the time that the stick is being held in stock and prior to use.
This resiliency, and tendency of the stick to grow after compaction, is vexing, because a stick must be compacted to a shorter length in order to accomodate the expected longitudinal growth. Growth also has the effect of reducing the pack ratio of the stick.
Various methods have been tried, and are presently employed, to counteract the resiliency of shirred casing sticks. These include, for example, adjustments in compacting methods, and use of various capturing means for resisting stick growth.
The former is illustrated by U.S. Pat. No. 3,209,398 where several applications of gradually increasing compaction force are used to compact the stick in order to reduce the tendency of the stick to return to its uncompressed length. In still another compaction method, the stick is held under compression for an extended period of time to reduce the resiliency of the stick.
A copending application of Mahoney, et al, Ser. No. 363,851 filed Apr. 5 1982, shows that shirred casing lengths can be highly compacted about a core member to achieve higher than conventional pack ratios. In this application, the pleats of the compacted casing embrace about the core. Due to the frictional engagement between the core and the casing, use of a core will, to some extent, resist axial growth of the stick. However, growth can be reduced even further by providing capturing means in association with the core to fix or stop the axial growth of the ends of the compacted strand or stick. While restraining means to capture a compacted length of casing have been used in the prior art, they have been lacking in one or more desirable features.
One desirable feature is to restrain and capture the fully compacted, or shortest length. To do this, the ends of the stick must be captured while maintaining the application of the compaction force. Any release of the compacting force in order to effect capture will permit the stick to grow so that something longer than the fully compacted length is captured.
Another desirable feature is that the capturing means should permit the casing to deshirr during the stuffing operation without the need for a separate operation to remove or open the capturing means.
It is also known in the art to place the stick in a retaining carton, either after doffing, as in U.S. Pat. No. 2,001,461, or prior to doffing, as in U.S. Pat. Nos. 2,010,626 and 2,028,691. However, such a restraint must be removed prior to utilization of the stick. Also, such cartons are not appropriate for highly compacted strands which can exert an axial force of 1000 pounds or higher when expanding.
In cases where the casing is carried on a core member, it is known to insert pegs through the core to keep the casing on the core. In other cases, removable washers have been used to restrain one or both ends of the casings (See U.S. Pat. No. 3,826,853 and UK Pat. No. 942,207). UK Pat. Nos. 1,167,377 and 1,104,528 show arrangements where one or both ends of a core member are flared or flanged, to hold the length of a shirred casing. However these patents only mention the retention of shirred casing and do not appear to contemplate retention of a length of casing which has undergone a further compaction step. As set out above, compacted casing may exert axial forces of up to 1000 pounds or more. The inflatable core, or the arrangement of tape, washers or tabs, as disclosed in these patents, would be unable to restrain the axial growth of such casing. Moreover, the restraining means, as taught in these patent, would have to be removed to permit deshirring, which is a still further drawback.
The present invention not only provides for effecting a capture of a fully compacted length of casing, but also allows deshirring without the need to remove the capturing means. Capturing the fully compacted length insures that the stick is maintained at substantially its shortest compacted length; namely, its length while still subjected to the compaction force. Allowing the casing to deshirr without removing the restraining means saves time and effort during the stuffing operation.
In the present invention, the strand of shirred casing is compacted about a core member and, while maintaining the compacting forces, the ends of the compacted casing are captured to the core. This is accomplished in various ways such as, for example, expanding the ends of the core while maintaining the application of the casing compacting forces.